Substrate processing apparatus, substrate processing method, and chemical liquid

ABSTRACT

A substrate processing method includes: supplying a first processing liquid containing a chelating agent and a solvent from a first tank toward a substrate having a film of a metal formed on a surface thereof to generate a complex containing the metal and the chelating agent while rotating the substrate; and supplying a second processing liquid containing water toward the substrate to dissolve the complex in the second processing liquid while rotating the substrate, after the complex is generated.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 17/154,049, filed on Jan. 21, 2021, which claims priority fromJapanese Patent Application Nos. 2020-009326 and 2020-165067, filed onJan. 23, 2020 and Sep. 30, 2020, respectively, with the Japan PatentOffice, all of which are incorporated herein in their entireties byreference.

TECHNICAL FIELD

The present disclosure relates to a substrate processing apparatus, asubstrate processing method, and a chemical liquid.

BACKGROUND

In a semiconductor manufacturing process, an etching method has beenknown in which a part of a metal film formed on a substrate such as asemiconductor wafer is removed by supplying an etching liquid whichcontains a chelating agent and has a pH of 7 or more to the metal film(see, e.g., Japanese Patent Laid-Open Publication No. 2018-181984).

SUMMARY

A substrate processing apparatus according to one aspect of the presentdisclosure includes a substrate rotator configured to hold and rotate asubstrate including a film of a metal formed on a surface thereof, afirst supply configured to supply a first processing liquid containing achelating agent and a solvent toward the substrate, a second supplyconfigured to supply a second processing liquid containing water towardthe substrate, and a controller configured to control the substraterotator, the first supply, and the second supply. While rotating thesubstrate by the substrate rotator, the controller supplies the firstprocessing liquid toward the substrate by the first supply to generate acomplex containing the metal and the chelating agent, and after thecomplex is generated, supplies the second processing liquid toward thesubstrate by the second supply to dissolve the complex in the secondprocessing liquid.

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the drawings and the followingdetailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are explanatory diagrams of an outline of a substrateprocessing method according to an embodiment.

FIGS. 2A to 2E are explanatory diagrams of details of the substrateprocessing method according to the embodiment.

FIG. 3 is a diagram illustrating a schematic configuration of asubstrate processing system according to the embodiment.

FIG. 4 is a diagram illustrating a schematic configuration of an etchingunit.

FIG. 5 is a flowchart illustrating a sequence of a substrate processingexecuted by the substrate processing system.

FIG. 6 is a flowchart illustrating a first example of a sequence of anetching processing.

FIG. 7 is a flowchart illustrating a second example of a sequence of anetching processing.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. The illustrativeembodiments described in the detailed description, drawings, and claimsare not meant to be limiting. Other embodiments may be utilized, andother changes may be made without departing from the spirit or scope ofthe subject matter presented here.

Hereinafter, an embodiment of the present disclosure will be describedwith reference to the drawings. In each drawing, the same orcorresponding components will be designated by the same or correspondingreference numerals and descriptions thereof will be omitted.

1. Substrate Processing Method

First, an outline of a substrate processing method according to anembodiment will be described with reference to FIGS. 1A and 1B. FIGS. 1Aand 1B are explanatory diagrams of an outline of a substrate processingmethod according to an embodiment.

As illustrated in FIGS. 1A and 1B, the substrate processing methodaccording to the embodiment is a method of thinning a metal film 110formed on a substrate (hereinafter, referred to as wafer W) such as asemiconductor wafer by removing a part of the metal film 110. The metalfilm 110 is provided inside a recess 121 such as a wiring groove or viahole formed in an interlayer insulating film 120. The interlayerinsulating film 120 is, for example, a low dielectric constant film(low-k film), and is formed on the surface of the wafer W. For example,before a processing, the surface of the metal film 110 is flush with thesurface of the interlayer insulating film 120 as illustrated in FIG. 1A,and after a processing, the surface of the metal film 110 is locatedcloser to the wafer W than the surface of the interlayer insulating film120 as illustrated in FIG. 1B. The substrate processing method of thepresent disclosure is not limited to the method of thinning the metalfilm 110 in the recess 121 as in the present embodiment, and may beused, for example, for precise etching of the entire surface of thewafer W.

Next, details of the substrate processing method according to theembodiment will be described with reference to FIGS. 2A to 2E. FIGS. 2Ato 2E are explanatory diagrams of details of the substrate processingmethod according to the embodiment. FIGS. 2A to 2E illustrates a changein the region R indicated by the two-dot dash line in FIGS. 1A and 1B.

In the substrate processing method according to the embodiment, first, afirst processing liquid containing a chelating agent and a solvent issupplied to the metal film 110. As illustrated in FIG. 2A, the metalfilm 110 contains metal atoms 111, and a passivation film 130 made of,for example, an oxide 131 of the metal atoms 111 is formed on thesurface of the metal film 110. For example, the passivation film 130illustrated in FIG. 2A is a natural oxide film, and has a thicknessequivalent to one atomic layer of the metal atoms 111. By supplying afirst processing liquid 210 containing a chelating agent 211 and asolvent 212 to the metal film 110, a part of the chelating agent 211adheres to the oxide 131 to generate a complex 213 containing the oxide131 and the chelating agent 211, as illustrated in FIG. 2B. Since theoxide 131 contains the metal atoms 111, the complex 213 contains themetal atoms 111 and the chelating agent 211. The complex 213 isdifficult to be dissolved in the solvent 212.

Subsequently, as illustrated in FIG. 2C, a third processing liquid 230that is water soluble is supplied to the metal film 110. As a result,the complex 213 continues to remain on the metal film 110 as it is, andthe chelating agent 211 that did not adhere to the oxide 131 and thesolvent 212 are replaced by the third processing liquid 230.

Subsequently, as illustrated in FIG. 2D, a second processing liquid 220containing water is supplied to the metal film 110. As a result, thecomplex 213 is dissolved in the second processing liquid 220. The secondprocessing liquid 220 inevitably contains dissolved oxygen. Therefore,when the complex 213 is dissolved in the second processing liquid 220,the metal atoms 111 located immediately below the dissolved complex 213are oxidized by the dissolved oxygen, and a new oxide 131 starts to begenerated.

When all of the complex 213 is dissolved in the second processing liquid220, as illustrated in FIG. 2E, a new passivation film 130 made of thenew oxide 131 is formed on the entire surface of the metal film 110.Further, the complex 213 is dissolved in the second processing liquid220 and removed from the metal film 110.

In this way, the atomic layer of the metal atoms 111 may be removed fromthe metal film 110 one by one. Further, by repeating the processing fromthe supply of the first processing liquid 210 (FIG. 2B) to the removalof the complex 213 (FIG. 2E), the atomic layer is removed from the metalfilm 110 one by one, which may allow the metal film 110 to be thinned bya plurality of atomic layers of the metal atoms 111.

Then, when the metal film 110 becomes thinner by a predeterminedthickness, the supply of all of the first processing liquid 210, thesecond processing liquid 220, and the third processing liquid 230 isstopped, and the wafer W is rotated to achieve the drying of the waferW.

With the substrate processing method according to the embodiment, it ispossible to suppress the surface roughness of the metal film 110 afteretching. In other words, the metal film 110 may be thinned whilemaintaining the surface of the metal film 110 flat (see FIG. 1B).

The wafer W may be dried between the removal of the complex 213 (FIG.2E) and the next supply of the first processing liquid 210 (FIG. 2B).Even when the passivation film 130 is not sufficiently formed when thecomplex 213 is dissolved in the second processing liquid 220, theformation of the passivation film 130 may be promoted by drying thewafer W.

Further, light etching of the metal film 110 may be performed as apretreatment before the first supply of the first processing liquid 210(FIG. 2B). The pretreatment may be performed by using, for example, afourth processing liquid to remove foreign substances such as organicmatters adhering to the surface of the passivation film 130. By removingthe foreign substances in advance, it becomes easier to keep the surfaceof the metal film 110 flat.

The chelating agent 211 contained in the first processing liquid 210contains, for example, an organic acid containing one or more selectedfrom the group consisting of a carbonyl group, a carboxyl group, and anamine group. Examples of such an organic acid include citric acid,oxalic acid, malic acid, maleic acid, iminodiacetic acid andethylenediaminetetraacetic acid (EDTA). The chelating agent 211contained in the first processing liquid 210 may be a chelating agentcapable of coordinating with the oxide 131 of a metal (target metal)constituting the metal film 110 which is a processing target. Examplesof the chelating agent 211 may include citric acid and oxalic acid whichmay be used when the target metal is cobalt, and oxalic acid which maybe used when the target metal is copper.

Examples of the solvent 212 contained in the first processing liquid 210may include isopropyl alcohol (IPA). The solvent 212 may contain one ormore selected from the group consisting of isopropyl alcohol, acetone,N-methyl-2-pyrrolidone (NMP), and tetrahydrofuran.

The first processing liquid 210 may contain water in addition to thechelating agent 211 and the solvent 212, but the content of water in thefirst processing liquid 210 may be preferably 10 mass % or less, andmore preferably 1 mass % or less. Even more preferably, the firstprocessing liquid 210 may be made of the chelating agent 211 and thesolvent 212. The first processing liquid 210 is an example of a chemicalliquid.

Examples of the second processing liquid 220 may include a processingliquid having an action of reacting the surface of the metal film 110with the chelating agent 211 to generate the complex 213. Examples ofthe second processing liquid 220 may include deionized water (DIW). Thesecond processing liquid 220 may be an aqueous solution in which a pHadjuster such as ammonia (NH₃) or carbon dioxide (CO₂) is dissolved inDIW. In order to suppress etching of the metal film 110 by the secondprocessing liquid 220, the pH of the second processing liquid 220 may be7 or more.

Examples of the third processing liquid 230 may include IPA. IPA may bedesired because it is easily dissolved in the second processing liquid220 containing water. The same liquid (or component) may be used for thesolvent 212 and the third processing liquid 230, and the liquid (orcomponent) of the solvent 212 and the liquid (or component) of the thirdprocessing liquid 230 may be different.

Examples of the fourth processing liquid may include an aqueous solution(SCI liquid) of NH₄OH (ammonium hydroxide) and H₂O₂ (hydrogen peroxide),or dilute hydrofluoric acid (DHF). Warmed IPA may be used as the fourthprocessing liquid.

2. Configuration of Substrate Processing System

Next, a configuration of a substrate processing system which executesthe above-described substrate processing method will be described withreference to FIG. 3 . FIG. 3 is a diagram illustrating a schematicconfiguration of a substrate processing system according to theembodiment. In the following, in order to clarify positionalrelationships, the X-axis, Y-axis, and Z-axis which are orthogonal toeach other will be defined, and the positive Z-axis direction will beregarded as a vertically upward direction.

As illustrated in FIG. 3 , the substrate processing system 1 includes acarry-in/out station 2 and a processing station 3. The carry-in/outstation 2 and the processing station 3 are provided adjacent to eachother.

The carry-in/out station 2 includes a carrier placing section 11 and atransfer section 12. In the carrier placing section 11, a plurality ofcarriers C are placed to accommodate a plurality of wafers Whorizontally.

As described above, the interlayer insulating film 120 is formed on thesurface of the wafer W, and the metal film 110 is formed in the recess121 such as a wiring groove or via hole formed in the surface of theinterlayer insulating film 120.

The transfer section 12 is provided adjacent to the carrier placingsection 11, and includes a substrate transfer device 13 and a deliveryunit 14. The substrate transfer device 13 includes a wafer holdingmechanism configured to hold the wafer W. Further, the substratetransfer device 13 is movable horizontally and vertically and pivotablearound a vertical axis, and transfers the wafer W between the carriers Cand the delivery unit 14 by using the wafer holding mechanism.

The processing station 3 is provided adjacent to the transfer section12. The processing station 3 includes a transfer section 15 and aplurality of etching units 16. The plurality of etching units 16 arearranged at both sides of the transfer section 15. The number of etchingunits 16 is not limited to the example illustrated in FIG. 3 .

The transfer section 15 includes a substrate transfer device 17 therein.The substrate transfer device 17 includes a wafer holding mechanismconfigured to hold the wafer W. Further, the substrate transfer device17 is movable horizontally and vertically and pivotable around avertical axis, and transfers the wafer W between the delivery unit 14and the etching units 16 by using the wafer holding mechanism.

The etching units 16 perform a predetermined substrate processing on thewafers W transferred by the substrate transfer device 17.

Further, the substrate processing system 1 includes a control device 4.The control device 4 includes a controller 18 and a storage unit 19.

The controller 18 includes, for example, a microcomputer having acentral processing unit (CPU), a read only memory (ROM), a random accessmemory (RAM), and input and output ports, or various circuits. Thecontroller 18 controls the operations of the substrate processing system1 as the CPU executes a program stored in the ROM by using the RAM as awork area.

The program may be recorded in a computer-readable storage medium andinstalled from the storage medium to the storage unit 19 of the controldevice 4. The computer-readable storage medium may be, for example, ahard disk (HD), a flexible disk (FD), a compact disk (CD), a magnetoptical disk (MO), or a memory card.

The storage unit 19 is implemented by, for example, a semiconductormemory device such as a RAM or a flash memory, or a storage device suchas a hard disk or an optical disk.

3. Configuration of Etching Unit

Next, a configuration of the etching unit 16 will be described withreference to FIG. 4 . FIG. 4 is a diagram illustrating a schematicconfiguration of the etching unit 16.

As illustrated in FIG. 4 , the etching unit 16 includes a chamber 20, asubstrate holding mechanism 30, a first supply 41, a second supply 42, athird supply 43, a fourth supply 44, and a recovery cup 50.

The chamber 20 accommodates the substrate holding mechanism 30, thefirst supply 41, the second supply 42, the third supply 43, the fourthsupply 44, and the recovery cup 50. A fan filter unit (FFU) 21 isprovided on the ceiling of the chamber 20. The FFU 21 forms a downflowin the chamber 20.

The substrate holding mechanism 30 includes a holder 31, a support 32,and a drive 33. The holder 31 holds the wafer W horizontally. The waferW is held by the holder 31 with the surface thereof on which the metalfilm 110 is formed facing upward.

In the present embodiment, the holder 31 includes a plurality ofgrippers 31 a and holds the wafer W by gripping the peripheral edgeportion of the wafer W using the plurality of grippers 31 a, but is notlimited to this. The holder 31 may be, for example, a vacuum chuck thatsucks and holds the wafer W.

The support 32 is a vertically extending member, and has a base endportion supported rotatably by the drive 33 and a tip end portionsupporting the holder 31 horizontally. The drive 33 rotates the support32 around the vertical axis. The substrate holding mechanism 30 rotatesthe holder 31 supported on the support 32 by rotating the support 32using the drive 33, thereby rotating the wafer W held in the holder 31.

The first supply 41, the second supply 42, the third supply 43, and thefourth supply 44 are arranged above the wafer W held in the holder 31.

One end of a first supply path 61 is connected to the first supply 41,and the other end of the first supply path 61 is connected to a firstsupply source 71 of the first processing liquid 210. A first flow rateadjusting valve 81 capable of adjusting an opening/closing operation ofthe first supply path 61 and the supply flow rate of the firstprocessing liquid 210 is inserted in the middle of the first supply path61. Thus, when the first flow rate adjusting valve 81 is opened, thefirst processing liquid 210 is supplied from the first supply 41 to thewafer W held in the holder 31. Thus, the first processing liquid 210 issupplied to the metal film 110 on the wafer W.

One end of a second supply path 62 is connected to the second supply 42,and the other end of the second supply path 62 is connected to a secondsupply source 72 of the second processing liquid 220. A second flow rateadjusting valve 82 capable of adjusting an opening/closing operation ofthe second supply path 62 and the supply flow rate of the secondprocessing liquid 220 is inserted in the middle of the second supplypath 62. Thus, when the second flow rate adjusting valve 82 is opened,the second processing liquid 220 is supplied from the second supply 42to the wafer W held in the holder 31. Thus, the second processing liquid220 is supplied to the metal film 110 on the wafer W.

One end of a third supply path 63 is connected to the third supply 43,and the other end of the third supply path 63 is connected to a thirdsupply source 73 of the third processing liquid 230. A third flow rateadjusting valve 83 capable of adjusting an opening/closing operation ofthe third supply path 63 and the supply flow rate of the thirdprocessing liquid 230 is inserted in the middle of the third supply path63. Thus, when the third flow rate adjusting valve 83 is opened, thethird processing liquid 230 is supplied from the third supply 43 to thewafer W held in the holder 31. Thus, the third processing liquid 230 issupplied to the metal film 110 on the wafer W.

One end of a fourth supply path 64 is connected to the fourth supply 44,and the other end of the fourth supply path 64 is connected to a fourthsupply source 74 of the fourth processing liquid. A fourth flow rateadjusting valve 84 capable of adjusting an opening/closing operation ofthe fourth supply path 64 and the supply flow rate of the fourthprocessing liquid is inserted in the middle of the fourth supply path64. Thus, when the fourth flow rate adjusting valve 84 is opened, thefourth processing liquid is supplied from the fourth supply 44 to thewafer W held in the holder 31. Thus, the fourth processing liquid issupplied to the metal film 110 on the wafer W.

The recovery cup 50 is disposed so as to surround the holder 31, andcollects the first processing liquid 210, the second processing liquid220, the third processing liquid 230, or the fourth processing liquidscattered from the wafer W by the rotation of the holder 31. A drainport 51 is formed in the bottom of the recovery cup 50, and the firstprocessing liquid 210, the second processing liquid 220, the thirdprocessing liquid 230, or the fourth processing liquid collected by therecovery cup 50 is discharged from the drain port 51 to the outside ofthe etching unit 16. Further, an exhaust port 52 is formed in the bottomof the recovery cup 50 to discharge a gas supplied from the FFU 21 tothe outside of the etching unit 16.

For example, when the metal film 110 is a cobalt film, i.e., when thetarget metal is cobalt, the first processing liquid 210, the secondprocessing liquid 220, the third processing liquid 230, and the fourthprocessing liquid may be used as follows. For example, the firstprocessing liquid 210 contains citric acid or oxalic acid as a chelatingagent and IPA as a solvent. For example, the second processing liquid220 is DIW, the third processing liquid 230 is IPA, and the fourthprocessing liquid is an SC1 liquid or DHF. The pH of DIW as the secondprocessing liquid 220 may be adjusted to more than 7 by a pH adjustersuch as NH₃.

4. Specific Operation of Substrate Processing System

Next, a specific operation of the substrate processing system 1 will bedescribed with reference to FIG. 5 . FIG. 5 is a flowchart illustratinga sequence of a substrate processing executed by the substrateprocessing system. Each device included in the substrate processingsystem 1 executes each processing sequence illustrated in FIG. 5 underthe control of the controller 18.

As illustrated in FIG. 5 , in the substrate processing system 1, first,the wafer W is carried into the etching unit 16 (step S101).Specifically, the substrate transfer device 13 of the carry-in/outstation 2 takes out the wafer W from the carrier C placed on the carrierplacing section 11, and places the taken-out wafer W on the deliveryunit 14. The wafer W placed on the delivery unit 14 is taken out fromthe delivery unit 14 by the substrate transfer device 17 of theprocessing station 3 and is carried into the etching unit 16. The waferW carried into the etching unit 16 is held by the holder 31 of theetching unit 16.

Subsequently, in the substrate processing system 1, an etchingprocessing is performed (step S102). In the etching processing, theprocessing liquids are supplied from the first supply 41, the secondsupply 42, the third supply 43, and the fourth supply 44 to the wafer Wheld in the holding unit 31 while the holding unit 31 holding the waferW is being rotated by the drive 33. Thus, a part of the metal film 110on the wafer W is removed.

Here, the details of the etching processing will be described. FIG. 6 isa flowchart illustrating a first example of a sequence of an etchingprocessing. FIG. 7 is a flowchart illustrating a second example of asequence of an etching processing.

In the first example, in the etching processing (step S102), first, apretreatment is performed (step S201). In the pretreatment, the fourthprocessing liquid is supplied from the fourth supply 44 to the rotatingwafer W, so that foreign substances such as organic matters adhering tothe surface of the passivation film 130 are removed by the fourthprocessing liquid.

Subsequently, a rinse processing is performed (step S202). In the rinseprocessing, the supply of the fourth processing liquid is stopped, and arinse liquid is supplied to the rotating wafer W. Thus, the fourthprocessing liquid remaining on the wafer W is removed. The rinse liquidis, for example, DIW. When the second processing liquid 220 is DIW, thesecond processing liquid 220 may be used as the rinse liquid. When thesecond processing liquid 220 contains, for example, a pH adjuster inaddition to DIW, a fifth supply connected to a DIW supply source may beprovided in the etching unit 16 to supply DIW as the rinse liquid fromthe fifth supply.

Thereafter, a drying processing is performed (step S203). In the dryingprocessing, the supply of the rinse liquid is stopped while continuingthe rotation of the wafer W. Thus, the rinse liquid remaining on thewafer W is removed, and the wafer W is dried. During the dryingprocessing, a natural oxide film is formed on the surface of the metalfilm 110 as the passivation film 130 containing the oxide 131 (see FIG.2A).

Subsequently, a complexation processing is performed (step S204). In thecomplexation processing, the first processing liquid 210 containing thechelating agent 211 and the solvent 212 is supplied from the firstsupply 41 to the rotating wafer W to generate the complex 213 containingthe oxide 131 and the chelating agent 211 (see FIG. 2B). The dryingprocessing (step S203) may be omitted, and the rinse processing (stepS202) may be followed by the complexation processing (step S204).

Subsequently, a purge processing is performed (step S205). In the purgeprocessing, the supply of the first processing liquid 210 is stopped,and the third processing liquid 230 is supplied from the third supply 43to the rotating wafer W to remove the chelating agent 211 which did notadhere to the oxide 131 and the solvent 212 and to form a liquid film ofthe third processing liquid 230 (see FIG. 2C).

Thereafter, a dissolution processing is performed (step S206). In thedissolution processing, the supply of the third processing liquid 230 isstopped, and the second processing liquid 220 is supplied from thesecond supply 42 to the rotating wafer W to dissolve the complex 213 inthe second processing liquid 220 and remove the complex 213 from themetal film 110 and to form the new passivation film 130 by dissolvedoxygen in the second processing liquid 220 (see FIGS. 2D and 2E).

Then, the processings of steps S204 to S206 are repeated, and theetching processing (step S102) is completed when the number ofrepetitions reaches a predetermined number of times (step S207).

After the etching processing (step S102), the rinse processing isperformed in the substrate processing system 1 (step S103). In the rinseprocessing, the supply of the second processing liquid 220 is stopped,and the rinse liquid is supplied to the rotating wafer W. Thus, thesecond processing liquid 220 remaining on the wafer W is removed. Whenthe second processing liquid 220 is DIW, the rinse processing (stepS103) may be omitted.

Subsequently, in the substrate processing system 1, a drying processingis performed (step S104). In the drying processing, the supply of therinse liquid is stopped while continuing the rotation of the wafer W.Thus, the rinse liquid remaining on the wafer W is removed and the waferW is dried. IPA may be used to assist in drying.

Subsequently, in the substrate processing system 1, a carry-outprocessing is performed (step S105). In the carry-out processing, thewafer W after the drying processing is carried out from the etching unit16 by the substrate transfer device 17, and is placed on the deliveryunit 14. Then, the completely processed wafer W placed on the deliveryunit 14 is returned to the carrier C of the carrier placing section 11by the substrate transfer device 13. Thus, a series of substrateprocessings for one wafer W is completed.

In the second example, first, the processings from the pretreatment(step S201) to the dissolution processing (step S206) are performed asin the first example.

Then, the processings of steps S204 to S206 are repeated, and a dryingprocessing (step S308) is performed when the number of repetitionsreaches a first predetermined number of times (step S307). In the dryingprocessing, the supply of the second processing liquid 220 used in thedissolution processing is stopped while continuing the rotation of thewafer W. Thus, the second processing liquid 220 remaining on the wafer Wis removed, and the wafer W is dried. The passivation film 130 formed inthe dissolution processing remains as it is.

Then, the repetition of the processings of steps S204 to S206 and thedrying processing of step S308 are repeated, and the etching processing(step S102) is completed when the number of repetitions reaches a secondpredetermined number of times (step S309).

For example, the first predetermined number of times is 10 times to 50times, and the second predetermined number of times is 3 times to 10times. When the first predetermined number of times is 40 times and thesecond predetermined number of times is 5 times, the processings ofsteps S204 to S206 are first repeated 40 times, and then the dryingprocessing of step S308 is performed. The processings of steps S204 toS206 repeated 40 times and the drying processing of step S308 are set toone set, and this set is repeated 5 times.

The first predetermined number of times may change during the etchingprocessing of step S102. In this case, the first predetermined number oftimes may decrease as the number of repetitions of the repetition of theprocessings of steps S204 to S206 and the drying processing of step S308increases. For example, when the second predetermined number of times is5 times, the first predetermined number of times may be 40 times whilethe number of repetitions of the repetition of the processings of stepsS204 to S206 and the drying processing of step S308 is up to 3 times,and may be 30 times during the remaining number of repetitions of 2times. In the later stage of the etching processing, a height differencebetween the surface of the metal film 110 and the surface of theinterlayer insulating film 120 increases, so that it is difficult toreplace the second processing liquid 220 with the first processingliquid 210 in step S204, which may make it difficult to generate thecomplex 213. Meanwhile, by reducing the first predetermined number oftimes in the later stage of the etching processing to increase thefrequency of the drying processing of step S308, the second processingliquid 220 may be removed before step S204 to maintain ease in thegeneration of the complex 213 in step S204.

When a liquid film of the second processing liquid 220 is formed on theentire surface of the wafer W in the dissolution processing (step S206),the controller 18 may stop the supply of the second processing liquid220 by the second supply 42 while continuing the rotation of the waferW. As described above, the new passivation film 130 is formed on thesurface of the metal film 110 with the supply of the second processingliquid 220. At this time, when the metal film 110 is exposed to thesecond processing liquid 220 for a long time, the newly generated oxide131 may be dissolved in the second processing liquid 220. When the newlygenerated oxide 131 is dissolved in the second processing liquid 220, itmay be difficult to remove the metal film 110 by each layer of the metalatoms 111.

The timing at which the supply of the second processing liquid 220 bythe second supply 42 is stopped may not completely coincide with thetiming at which the formation of the liquid film is completed. Forexample, assuming that the time from the start of the supply of thesecond processing liquid 220 to the completion of the formation of theliquid film is t, the supply of the second processing liquid 220 may bestopped when the time of 1.0 t or more and 1.1 t or less has passed fromthe start of the supply of the second processing liquid 220.

The controller 18 may control the temperature of the second processingliquid 220 to 25° C. or lower. This is because the newly generated oxide131 is easily dissolved in the second processing liquid 220 when thetemperature of the second processing liquid 220 is more than 25° C. Forexample, the controller 18 controls the temperature of the secondprocessing liquid 220 to 20° C. or more and 25° C. or less which isabout room temperature. The controller 18 may control the temperature ofthe third processing liquid 230 to the same degree as the temperature ofthe second processing liquid 220. This is to suppress a change in thetemperature of the second processing liquid 220 supplied to the wafer W.

The controller 18 may control the concentration of dissolved oxygen inthe second processing liquid 220 to 600 ppb or less, and moreparticularly to 500 ppb or less. This is because the passivation film130 may be excessively formed when the concentration of dissolved oxygenin the second processing liquid 220 exceeds 600 ppb. Meanwhile, it isextremely difficult to reduce the concentration of dissolved oxygen toless than 100 ppb. Further, when the concentration of dissolved oxygenis too low, it may be difficult to form the new passivation film 130.Thus, the controller 18 sets the concentration of dissolved oxygen inthe second processing liquid 220 to 100 ppb or more and 600 ppb or less.

The controller 18 may control the pH of the second processing liquid 220according to the type of the target metal. A pH adjuster may be used tocontrol the pH. By controlling the pH of the second processing liquid220, the etching of the passivation film 130 by the second processingliquid 220 such as DIW may be suppressed. For example, when the targetmetal is cobalt or copper, NH₃ may be used as the pH adjuster.

As described above, the substrate processing system 1 (an example of thesubstrate processing apparatus) according to the embodiment includes thesubstrate holding mechanism 30 (an example of the substrate rotator),the first supply 41, the second supply 42, and the controller 18. Thesubstrate holding mechanism 30 holds and rotates the wafer W (an exampleof the substrate) having the metal film 110 formed on the surfacethereof. The first supply 41 supplies the first processing liquid 210containing the chelating agent 211 and the solvent 212 toward the waferW. The second supply 42 supplies the second processing liquid 220containing water toward the wafer W. The controller 18 controls thesubstrate holding mechanism 30, the first supply 41, and the secondsupply 42. The controller 18 supplies the first processing liquid 210toward the wafer W by the first supply 41 to generate the complex 213containing a metal constituting the metal film 110 and the chelatingagent 211 while rotating the wafer W by the substrate holding mechanism30, and after the generation of the complex 213, supplies the secondprocessing liquid 220 toward the wafer W by the second supply 42 todissolve the complex 213 in the second processing liquid 220.

Accordingly, with the substrate processing system 1 according to theembodiment, it is possible to suppress the surface roughness of themetal film 110 after etching.

The target metal is not limited to cobalt (Co) and copper (Cu). Forexample, the target metal may be ruthenium (Ru), molybdenum (Mo), ortitanium nitride (TiN).

The substrate processing system 1 may be provided with a first tankwhich stores the first processing liquid 210 and a second tank whichmixes the chelating agent and the solvent, and the chelating agent andthe solvent may be supplied to the second tank from a supply source ofthe chelating agent and a supply source of the solvent, respectively. Inthis case, the chelating agent and the solvent are mixed in the secondtank, and a mixed liquid of the chelating agent and the solvent is sentfrom the second tank to the first tank as the first processing liquid210, so that the first processing liquid 210 is supplied from the firsttank to the first supply 41.

According to the present disclosure, it is possible to suppress thesurface roughness of a metal film after etching.

From the foregoing, it will be appreciated that various embodiments ofthe present disclosure have been described herein for purposes ofillustration, and that various modifications may be made withoutdeparting from the scope and spirit of the present disclosure.Accordingly, the various embodiments disclosed herein are not intendedto be limiting, with the true scope and spirit being indicated by thefollowing claims.

What is claimed is:
 1. A substrate processing method comprising:supplying a first processing liquid containing a chelating agent and asolvent from a first tank toward a substrate having a film of a metalformed on a surface thereof to generate a complex containing the metaland the chelating agent while rotating the substrate; and supplying asecond processing liquid containing water toward the substrate todissolve the complex in the second processing liquid while rotating thesubstrate, after the complex is generated.
 2. The substrate processingmethod according to claim 1, wherein the second processing liquid iswater or an aqueous solution.
 3. The substrate processing methodaccording to claim 1, wherein the supplying the second processing liquidincludes stopping the supply of the second processing liquid when aliquid film of the second processing liquid is formed on an entiresurface of the substrate.
 4. The substrate processing method accordingto claim 1, wherein the supplying the first processing liquid and thesupplying the second processing liquid are repeated.
 5. The substrateprocessing method according to claim 1, further comprising: supplying athird processing liquid that is water soluble toward the substrate toremove the chelating agent remaining on the substrate after the complexis generated and before the second processing liquid is supplied.
 6. Thesubstrate processing method according to claim 1, wherein a temperatureof the second processing liquid is controlled to 25° C. or less.
 7. Thesubstrate processing method according to claim 1, further comprising:supplying a fourth processing liquid capable of removing a foreignsubstance adhering to a surface of the film of the metal toward thesubstrate while rotating the substrate before the first processingliquid is supplied.
 8. The substrate processing method according toclaim 1, further comprising: continuously rotating the substrate to drythe surface of the substrate after the second processing liquid issupplied.
 9. The substrate processing method according to claim 1,wherein the first processing liquid and the second processing liquid aresupplied alternately for a first number of times, respecteively, whilerotating the substrate, after the alternate supplying of the firstprocessing liquid and the second processing liquid, a first drying isperformed on the surface of the substrate while continuing the rotationof the substrate, and the alternate supplying and the first drying arerepeated for a second number of times.
 10. The substrate processingmethod according to claim 9, wherein the first number of times of thealternate supplying is reduced as the number of the alternate supplyingand the first drying increases.
 11. The substrate processing methodaccording to claim 1, wherein the first processing liquid furtherincludes water and a content of water is 10 mass % or less.
 12. Thesubstrate processing method according to claim 1, wherein the metalincludes one or more selected from a group consisting of Cu, Co, Ru, Mo,and TiN, the chelating agent contains an organic acid containing atleast one selected from a group consisting of a carbonyl group, acarboxyl group, and an amine group, and the solvent contains one or moreselected from a group consisting of isopropyl alcohol, acetone,N-methyl-2-pyrrolidone, and tetrahydrofuran.